Aristotle, Metaphysics, Book 3 72:

ἐκ μὲν οὖν τούτων τῶν λόγων οὐκ ἂν εἰήσαν αἱ ἀρχαὶ τὰ γένη τῶν ὄντων:? εἰ δ ἕκαστον μὲν γνωρίζομεν διὰ τῶν ὁρισμῶν, ἀρχαὶ δὲ τὰ γένη τῶν ὁρισμῶν εἰσίν, ἀνάγκη καὶ τῶν ὁριστῶν ἀρχὰς εἶναι τὰ γένη.?